1. Technical Field
The present disclosure relates to monitoring a machine component, and in particular, to a system and method for optically monitoring contamination of a machine component, such as a printer machine component, utilizing fluorescent contaminant markers.
2. Description of Related Art
Modern machine designs utilize various “machine components” that are used together to fully construct the machine. These machine components may be replaceable and/or permanent. For example, modern printing systems utilize various modular and integrated machine components. Machine components utilized in printing systems are referred to herein as printer machine components. Monitoring of these printer machine components may be implemented using one or more strategically placed sensors. Some of these sensor may be optically based sensors. One such optical monitoring technique is described in the previously filed U.S. Patent Application entitled, “SYSTEM AND METHOD FOR MONITORING A PRINTING SYSTEM USING A CAMERA”, filed on Sep. 26, 2007 and assigned U.S. patent application Ser. No. 11/904,267, which has been assigned to the present assignee, and the entire contents thereof, are hereby incorporated by reference.
Many printer machine components are replaceable and have a limited shelf life and/or useful life. For example, in some color printing systems four types of toners are deposited on a printing substrate (e.g., paper) from one or more drums to form a toner image; however, the toner image initially deposited onto the paper is not fully secured to the paper. Moreover, the toner image initially deposited onto the paper does not have the desired gloss level. The toner image is permanently fixed to the paper and the desired gloss level in the image are both achieved by using a heat and pressure mechanism or a radiant fusing technology to melt and bond the toner particles to the medium being printed on (usually paper). This process is called fusing. These fusing members have a limited useful life.
One type of fusing member is a fuser roll. Typically, a pair of cylindrically shaped machine components forms the fuser rolls (one applies heat and the other applies pressure). The fuser rolls are used to fuse the toners to the paper. The toner image on the substrate initially has the consistency of loose powder. The substrate (e.g., paper) with the loose toner image is fed through the two fusing members where the toner image is heated while sufficient pressure is applied. The pressure and heat applied should be properly controlled to ensure that the toner image is adequately bonded to the substrate and to achieve the desired level of image gloss.
Another type of fusing member is a fuser belt. Rather than use a pair of fuser rolls, one or more belts are used to move the substrate along a path. The belt may be wrapped and/or guided along a path with various rollers and/or nips. One or more belts can carry the substrate with a loose toner image disposed thereon through a region of the printing system so that heat and/or pressure is applied to fuse the toner to the substrate.
The fuser belt and fuser roll are only two types of fusing members that can be utilized in the fusing process. Other fusing members include the various gears, nips, rollers and components used in the fusing process as well. One possible failure mode of fusing members is toner contamination. For example, fuser rolls eventually accumulate toner contamination levels that cause visible defects on the end product (e.g., a printed piece of paper). Fusing member contamination can cause various visible print quality defects associated with the toner offsetting onto the fuser member. Because of this type of failure mode, the fusing member(s) must be periodically replaced. This type of failure mode can account for a significant portion of the overall replacement costs of all of the printer machine components. One technology that extends the useful life of a fusing member is to continuously apply oil to the fusing member to prevent the toner from sticking thereto; although the useful life of the fusing member is extended, eventually it must be replaced.
One method of estimating contamination of the fusing member is destructive and off-line. This approach requires the removal of a strip of rubber from the fuser roll (or belt) with examination of the strip using Fourier transform infrared spectroscopy analysis of the sample to quantify the amount of various contaminants on the fuser roll (or belt). This method permanently disables the fusing member, is very expensive, and is not well suited for in situ diagnostics and/or feedback control.